[Research progress in establishing baselines and thresholds of influenza epidemic]

Influenza is an acute respiratory infection that seriously harms the world and public health. Because influenza viruses are prone to mutations and difficult to predict, the World Health Organization has been promoting global continuous strengthening of influenza surveillance to monitor the level of influenza activity and epidemic trends in real time. Establishing baselines and thresholds for influenza epidemic helps to gauge the start and severity of influenza seasons. At present, there are various methods for calculating baseline and threshold, such as annual median value, percentile approach, moving epidemic method, and control chart method. This paper will summarize the methods of establishing influenza baseline or threshold at home and abroad, and hope to provide reference for the establishment of baseline or threshold of influenza in China.